Synthesis Of N-trifluoromethylselenosaccharin And Application In Electrophilic Trifluoromethylselenolation

In view of the fact that the compounds containing CF₃Se have very good applications potential in new medicines and new materials.It is particularly important to design new trifluoromethylselenolation reagents and develop new methords for trifluoromethylselenolation reactions.So far,many reagents have been reported for trifluoromethylselenidation reaction,such as MSe CF₃（M=Hg,Ag,Cu）,（Me₄N）Se CF₃,[（bpy）Cu Se CF₃]₂,BT-Se CF₃,CF₃Se Cl,Ts Se CF₃,etc.However,these reagents suffer from the synthesis of complex reagents,the use of toxic excess transition metals,the need for higher reaction temperature,expensive substrate reagents.Therefore,it is still necessary to design and synthesize new trifluoromethyl-selenolation reagents.In this paper we have synthesized a novelly trifluoromethylselenolation reagent successfully,then,intensively researched the electrophilic substitution of（hetero）aromatic rings and oxy-trifluoromethylselenolation of olefins.The main research contents are as follows:1)A new electrophilic trifluoromethylselenolation reagent,N-trifluoromethylselenide saccharin,was designed and synthesized successfully,with CF₃Se Cl as raw material.The reaction conditions of the synthesis of N-trifluoromethylselenide saccharin were optimized.Finally,the optimal conditions were determined as follows:using dichloromethane as solvent,the ratio of Bn Se CF₃,SO₂Cl₂ and silver saccharin was 1:1.2:2,in 5 hours at room temperature.This reagent can be stored at-20℃for at least two months without any decompositions.Using N-trifluoromethylselenide saccharin as trifluoromethyl selenoting reagent,the free radical decarboxylation of N-p-toluenesulfonyl piperidine-4-carboxylic acid give trifluoromethyl-selenolation product correspounding can be realized in acetone/H₂O system at 80℃.2)Using N-trifluoromethylselenide saccharin,the electrophilic trifluoromethyl-selenidation of electron rich aromatic（hetero）substrates were directly realized without the participation of metals and other additives.Different substituted electron rich aromatic rings and aromatic heterocycles can be electrophilic trifluoromethylselenidation smoothly,and the corresponding trifluoromethylselenidation products can be obtained in good to excellent yields.The reaction has very good functional group compatibility,substrate universality,good chemoselectivity and regioselectivity.The reaction conditions are mild and efficent,which is very suitable for the late-stage modification of complex natural products and drug molecules.3)The oxytrifluoromethylselenolation of olefins was realized using N-trifluoromethyl-selenide saccharin.With the catalyzed of 9-thiotonone（5 mol%）,various of olefins and alcohols underwent oxytrifluoromethylselenidation reactions smoothly at room temperature,correspounding products was obtained in moderate to good yields.Most alcohols with electron donating groups have medium or above yields,while alcohols with electron absorbing groups have low yields.It’s worth noting that steric hindrance has a great influence on the reaction.The greater steric hindrance of alcohol,the lower reaction activity.On the basis of this experiment,we expect to expand the oxytrifluoromethylselenolation of different olefins use water and carboxylic acids as the oxygen source.